1. Field of the Invention
This invention relates to a method for applying an edge protector to a plate made of a brittle material, such as glass or a glass-ceramic or ceramic material, in particular a cooking surface.
2. Description of Related Art
In connection with cooking surfaces, in particular, it is important to protect a circumferential edge against damages, since this edge is particularly sensitive to mechanical stresses. If the edge of a plate made of a brittle material, such as glass or a glass-ceramic or a ceramic material, is badly or not at all treated, the mechanical stressing capability of the edge is reduced because of the poor condition of the surface.
Various steps for protecting the edges of such plates against breakage, cracks and indentations are already known.
As shown in German Patent Reference DE 33 41 191 A1, it is known to protect a cooking surface circumferentially with a metal frame, which is connected via a flowable sealing material with the cooking surface. The sealing material is extruded into a hollow space formed between the metal frame and the cooking surface, with the aid of sealing bars.
A two-component adhesive is preferably used as the sealing material, which is introduced under pressure into the hollow space and sets under the effect of heat.
By this method, manual gluing of the cooking surface into the metal frame is replaced by a work step which can be performed automatically, and which makes manufacture of the edge protector simple and cheaper.
However, this method still requires prefabricated metal frames, which are produced in an extrusion process with elaborate, pressure-resistant tools and require a pressure-resistant closure of the hollow spaces in the area of the edge of the plate.
It is also known to provide plates made of glass with an extruded frame of a thermoplastic material. Again, a high-cost tool is required because it must resist the high extrusion pressure. Furthermore, this extruded part has only the function of a metal frame, no elastic framing of the plate can thus be provided, unless silicon caoutchouc or PUR are used as the materials.
It is also known to produce the edge protector for a cooking surface by means of a directly foamed-on frame made of a plastic reaction foam, as shown by German Patent Reference DE 197 03 542 A1. Here, too, a closed tool is required, which must withstand the pressure occurring in the course of the reaction. Moreover, an appropriate setting time is required.
It is one object of this invention to provide a method of the type mentioned above, which does not require a prefabricated expensive frame and an elaborate pressure-resistant tool.
This object is achieved in accordance with this invention because a plate is positioned, with a top leading, in a lower tool element, and an upper tool element is placed on the lower tool element with the positioned plate. A hollow space, which is open toward the top of the upper tool element and defines the shape of the edge protector, is delimited by the lower tool element and the upper tool element in the area of the edge of the plate. A cold-setting sealing compound is metered into the hollow space, and the plate, together with the edge protector, is removed from the tool following the setting of the sealing compound.
By this manner of positioning the plate in the lower tool element, the edge protector is definitely delimited in its shape and fixed in the visible area, such as the top, of the plate. Because the back of the plate is normally not visible, something which is the case with cooking surfaces, the tool with the hollow space formed for the edge protector can be open toward that side.
The sealing compound can be metered in from this side. Because the sealing compound sets while it is cold, the tool need not be pressure-resistant, particularly since compensation openings are provided toward the top of the upper tool element. Moreover, a smooth edge protector is achieved in the visible area of the plate, and thus a porous appearance of the surface, such as in connection with a reaction foam material, is avoided.
Because of the open design of the tool, the method of this invention permits the employment of epoxy resins, hard woods or aluminum for the construction of the tool, which considerably reduces the production times for the latter, which in particular is a result of the sealing compound being introduced into the tool almost without pressure.
In accordance with one embodiment and depending on the use of the plate, it is possible to provide a low-viscosity sealing compound, such as polyurethane (PUR), silicon, epoxy resins or polyester, which is used for a permanently elastic edge protector. Low-melting metals, for example aluminum, are used for a shock-resistant edge protector, provided the casting tool is appropriately temperature-resistant.
Positioning of the plate in the lower tool element can be easier and improved because the plate is supported in the lower tool element in the area of the edge with a circumferential sealing element. Thus the hollow space is delimited toward the top and/or the edge of the plate. Moreover, damage to the plate at the support points of the tool are no longer a problem.
The same applies to the upper tool element if it is supported with a circumferential sealing element on an underside of the plate at a distance from the edge of the latter, by means of which the hollow space, and therefore the width of the edge protector, are delimited on the underside of the plate.
Since, following metering of the sealing compound, the unset edge protector is still accessible through the open upper tool element, it is possible to embed fastening elements, such as assembly aids, in the sealing compound introduced into the hollow space.